Sorption, degradation and mobility of microcystins in Chinese agriculture soils: Risk assessment for groundwater protection

In the present paper, sorption, persistence, and leaching behavior of three microcystin variants in Chinese agriculture soils were examined. Based on this study, the values of capacity factor and slope for three MCs variants in three soils ranged from 0.69 to 6.00, and 1.01 to 1.54, respectively. The adsorption of MCs in the soils decreased in the following order: RR > Dha(7) LR > LR. Furthermore, for each MC variant in the three soils, the adsorption rate in the soils decreased in the following order: soil A > soil C > soil B. The calculated half-time ranged between 7.9 and 17.8 days for MC-RR, 6.0-17.1 days for MC-LR, and 7.1-10.2 days for MC-Dha(7) LR. Results from leaching experiments demonstrated that recoveries of toxins in leachates ranged from 0-16.7% for RR, 73.2-88.9% for LR, and 8.9-73.1% for Dha 7 LR. The GUS value ranged from 1.48 to 2.06 for RR, 1.82-2.88 for LR, and 1.76-2.09 for Dha(7) LR. Results demonstrated the use of cyanobacterial collections as plant fertilizer is likely to be unsafe in soils. (c) 2006 Elsevier Ltd. All rights reserved.

Study of sorption, biodegradation and isomerization of HCH in stimulated sediment/water system

This paper reported the sorption, biodegradation and isomerization of hexachlorocyclohexane (HCH) in laboratory sediment/water system under aerobic and anaerobic conditions, respectively. The effect of organic nutrient addition to the sorption of HCH was also investigated. It indicates that HCH is highly adsorbed on sediments under both conditions. During the tests, the biodegradation and isomerization of HCH were dramatically speeded up after organic nutrient additions, especially in the case of the observation under aerobic condition. It was found, beta-HCH was the most persistent in the environment, that is due to the isomerization of alpha-HCH in a big amount to beta-HCH, besides its chemical stability. (C) 1997 Elsevier Science Ltd.

EDMOCSS-有毒有机化学品在土壤－植物系统中暴露动态的新模型研究－－菲（Phenanthrene)在沈阳西部城市污水慢速渗滤土地处理系统的暴露动态模拟

有毒有机污染物（TOP）在土壤－植物系统暴露动态模型是TOP生态风险评价和管理的必要手段，是目前TOP环境科学研究的活跃领域。以往主要以经典的对流－扩散方程（CDE）为基础的建模途径存在诸多局限：i.基本过程机制和理论研究尚不完善，制约着系统模型的研究水平；ii.模型过于复杂，在应用上存在很大困难，；iii.普遍缺乏野外实际观测结果的检验。需要开辟和发展新的TOP在土壤－植物系统暴露动态模型正是在此方面的突破。EDMOCSS很大程度上克服了经典建模途径的局限，既包括几乎所有基本过程及其目前普遍接受和应用的理论，模型的结构又不很复杂，具有良好行为特征，应用上较方便。以优先有机污染物－菲（phenanthrene)为供试化学品的野外慢速土地处理系统（SR－LTS）小区动态观察结果，很好地验证了EDMOCSS核心模型－耕作层土壤分室模型的结果，表明了EDMOCSS有较好模拟预测能力，为EDMOCSS的深入研究和应用奠定了基础。